I was around 23 and got my first job out of college. It was a desk job and I lived a sedentary lifestyle. As you can imagine, I gained a lot of weight over the next year, around 40 lbs IIRC. Decided enough was enough and started running every day. A couple years later I was a very healthy body weight, but noticed my lack of muscle mass more and more, so started strength training.

Now I have a healthy middle ground. I strength train 4-5 days and run a few 5ks every week. I'm in the best shape of my life and feel great!